The present invention relates to the field of devices and methods for improving hearing in hearing impaired persons and, more particularly, to external audio processors for use with implanted hearing devices.
Traditional hearing aids have generally been devices including a microphone, an amplifier and a speaker placed in a person's external ear canal. The microphone picks up ambient sounds which the amplifier amplifies and delivers to the speaker (also known as the "receiver"). The speaker broadcasts the amplified sound at a much louder level to the hearing impaired person. Recently, hearing aid devices have incorporated advanced integrated circuit designs that shape the amplified sounds to best suit the person's hearing loss. Although there have been numerous advancements in traditional hearing aid devices, inherent problems still remain.
Traditional hearing aid devices have the inherent problem of occlusion. The electronic components of the hearing aid are housed in a plastic or acrylic ear plug which is placed in the external ear canal. Placing the hearing aid in the ear canal diminishes the hearing impaired person's natural ability to hear by occluding the ear canal. Thus, traditional hearing aid devices cause the user to rely almost solely upon the hearing aid and the resulting occlusion is thought to be at least partially responsible for complaints of unnatural or poor sounding devices.
Traditional hearing aid devices also have the inherent problem of feedback. Feedback commonly occurs when a microphone is placed in close proximity to an amplified speaker output. As the microphone and the amplified speaker output of a hearing aid are in close proximity, there is an omnipresent opportunity for a feedback loop to be established resulting in an extremely loud "whistle" or "squeal" being broadcast from the device. In order to minimize feedback, the microphone and speaker should be acoustically isolated from one another. However, acoustic isolation usually involves reducing the vent tube volume which in turn increases the opportunity for feedback.
Implanted hearing devices have been designed that reduce many of the problems attendant with traditional hearing aids. Implanted hearing devices typically include a mechanical mechanism that is implanted in the middle or inner ear to vibrate middle or inner ear structures. The mechanical mechanism is typically driven by electronic signals from an external audio processor. Examples of these hearing devices are described in U.S. Pat. No. 5,015,224, issued May 14, 1991 to Maniglia, U.S. Pat. No. 4,606,329, issued Aug. 19, 1986 to Hough, and U.S. Pat. No. 5,282,858, issued Feb. 1, 1994 to Bisch et al.
Implanted hearing devices alleviate many of the problems associated with traditional hearing aid devices including occlusion and feedback. However, conventional implanted hearing devices still share many problems with traditional hearing aids.
Hearing devices in general are high maintenance devices. Battery doors and contacts continuously wear out and must be replaced. Also, microphones should be kept clean to operate properly. As hearing devices can easily be damaged, high levels of physical exercise or activity can generate problems. For these reasons and others, hearing devices are frequently returned to a hearing device dispenser or audiologist for service or repair which lowers the availability of the hearing device and increases the maintenance cost.
Hearing devices are generally very expensive to initially obtain. As the hearing device is expensive, many users do not have spare hearing devices. Thus, when a hearing device becomes inoperable or lost, the user generally has to forego assisted hearing until the hearing device is serviced or a new one is obtained.
What is needed is a device that alleviates common problems associated with traditional hearing aids like occlusion and feedback, and also solves the problems of maintenance, availability and cost associated with hearing devices in general. The present invention fulfills these and other needs.